The cold room refrigeration equipment of food storage is usually cooled by the refrigeration mechanism. The liquid (ammonia or Freon) with very low gasification temperature is used as a coolant to make it evaporate under the condition of low pressure and mechanical control, absorb the heat in the storage, to achieve the purpose of cooling. The most commonly used is a compression refrigerator, which is mainly composed of compressor, condenser and evaporation tube. According to the way of the evaporation tube device, it can be divided into direct cooling and indirect cooling. When the liquid coolant passes through the low-pressure evaporation pipe, it directly absorbs the heat in the warehouse and cools down. Indirect cooling is that the air in the warehouse is drawn into the air cooling device by the blower. After the air is absorbed by the evaporation pipe in the cooling device, it is sent to the warehouse for cooling. The advantages of air cooling mode are rapid cooling, the uniform temperature in the warehouse, and the harmful gases such as carbon dioxide produced in the storage process that can be taken out of the warehouse.
The temperature of food cold storage is generally - 15 ℃ ~ - 18 ℃. Generally, the food is put into the cold storage step by step irregularly. After a while, the temperature of the cold storage reaches - 18 ℃, and it is also irregular and irregular to pick up the goods. There is no specific requirement for this "time", which is a typical cold storage. For example, meat and aquatic products have higher storage temperature requirements, to keep the internal class from deterioration. And in the process of the sale, they are also taken out and stored irregularly. Generally, refrigerators in supermarkets are all refrigerated.
Common cooling methods include:
The air cooling method is used to blow cold air into the tunnel where food is placed, or use the pressure difference of 2000 kPa to make cold air enter and pass through the food packing box with air window, to accelerate the cooling of products. The temperature, relative humidity and flow rate of cold air are determined according to the type of food. Generally, food is not frozen. The relative humidity is usually 95%.
Classification and advantages and disadvantages of wall insulation in food cold storage
Wall insulation is mainly through the wall surface or internal treatment, which plays the role of energy conservation, protection of the main structure and prolonging the life of the building. Today's wall insulation can be divided into external wall external insulation system, external wall internal insulation system, external wall sandwich insulation system, external wall self insulation system according to the structure and location.
Cold processing of food can not improve the quality of food, only through low-temperature treatment, inhibit the activity of microorganisms, to achieve the purpose of long-term storage. Therefore, in the use of cold storage, the health management of cold room refrigeration equipment is an important work. It is necessary to strictly implement the relevant health regulations and minimize the opportunities of microbial contamination of food, to ensure the quality of food and extend the storage period. Food cold storage maintenance